This application is related to U.S. patent application Ser. No. 07/359,188 filed concomitantly herewith entitled "Annular Electrical Terminal".
Generally ring tongue terminals are used to interconnect a wire conductor member to an essentially flat current conducting member by means of a bolted joint wherein torque is applied to the joint until a sufficiently low resistance results. The ring tongue terminal includes an essentially flat mating surface that engages a flat surface of an article such as a bus bar or a printed circuit board.
To ensure a low interface resistance between the ring terminal and the flat member it is necessary to apply a considerable force to the joint until a sufficiently low resistance results. The amount of torque required depends upon the electrical system in which the terminal is being used. While a high mating torque may be applied to metal conductive members such as a bus bar, the same amount of force when applied to a ring terminal bolted to a circuit board may cause distortion of the circuit board. It is desirable therefore to have a terminal with a low interface resistance that does not require a large amount of force applied between the ring terminal member and the electrical article to which it is connected.
The area of electrical engagement of the ring terminals of the prior art typically provide a single "circular line" of contact between the surface of the terminal and the electrical article to which it is attached. In actuality this "circular line" consists of a plurality of randomly located points in physical engagement and electrical contact between the corresponding surfaces. The number of points along this "line" contact depends upon the amount of force applied between the two members, the surface finish and the flatness of the surface of the two members. It is desirable, therefore, to provide as many controlled parallel current paths as possible for the current to flow between the interconnected members.
The resistance between the mated surfaces is typically controlled by applying more force to increase the uniformity and width of the contact line or number of points in actual physical and electrical engagement between the members. The amount of force required at any one interconnection is generally determined by measuring the resistance after the interconnection is made and adjusting the force as necessary to achieve the desired results. It is desirable, therefore, to have a means whereby the amount of force required and the resistance of the interface may be calculated and predetermined before the interconnection is made.